Would the cell start bleeding power off sitting at an idle state by itself?
Others smarter than me, but I would check that. I have two 25 ah batteries at 24 volts each. I’m working on two 24 volt 8S 280 ah battery packs with the first on the charger now. All my cells were delivered good, except one I physically damaged. That’s why I have the odd sized battery pack with the 24 ah to 26 ah capacity.
I’d top balance all the cells I capacity tested and check voltages 24 hours off the top balance.
Putting together these cells is not a quick process, so that’s why I’d want to let it rest before I add it.
This is how I did the capacity test, although I used the DL24P which is a slightly different than his.
I capacity tested all 16 of my 25 ah cells, whitch took about three to four days. I don’t plan on doing all my 280 ah cells. Those could take weeks. Right now for my 280 ah cells, I plan on doing 4. I did get these cells from a reputable vendor.
When I did the capacity test, the voltage auto shut off at 2.5 volts. After resting, overnight, the voltage climbed back up to 2.8. That lets me think this cell you have may be fully discharged. To me, the only way this could be fully discharged that ends in a good scenario, is if the vendor capacity tested this cell and forgot to charge it afterwards. Maybe it was a quality control measure that ends quality control checked. Other than that, I can’t think of a good reason for it to be completely discharge.
Even after all these tests are done, my eyes would be glued to the BMS to see how that cell is doing. With the charging process and at sunset, I’m looking at battery voltages of individual cells, so if those cells drift apart, that’s when it would DEFINITELY be time to swap the cell.
All that work and waiting for the batteries, if I needed both batteries right away, I’d probably still do the tests I mentioned, ant if they did pass with flying colors, I‘d probably still order a replacement cell.